This invention relates to improvements in the art of manufacturing thermal insulation batts.
This invention provides process for preparing a fiberglass insulation product. The process of this invention includes the steps of: (a) providing a layer of kraft paper, (b) coating the kraft paper layer with a high melting point film such as high density polyethylene (HDPE) or of polypropylene form an HDPE-kraft laminate or a polypropylene-kraft laminate, (c) coating the HDPE-kraft laminate with a low melting point film such as low density polyethylene (LDPE) to form an LDPE-HDPE-kraft laminate or an LDPE-polypropylene-kraft laminate, (d) adjusting the temperature of the LDPE-HDPE-kraft laminate or the LDPE-polypropylene-kraft laminate so that the LDPE becomes tacky while the HDPE or polypropylene remains solid, (e) providing a layer of fiberglass wool, and (f) contacting the LDPE layer of the LDPE-HDPE-kraft laminate or of the LDPE-polypropylene-kraft laminate with the fiberglass wool layer to bond the LDPE-HDPE-kraft laminate or LDPE-polypropylene-kraft laminate to the fiberglass wool layer to form a fiberglass insulation product.
Thermal insulation batts are often comprised of a relatively thick layer of low density bulk insulating material, such as fiberglass wool, faced with for instance asphalt-coated kraft paper facing. The asphalt coating is used both to adhere the layer of thermal insulation to the facing and also to provide vapor barrier properties to the paper. Alternatively, foil-backed paper can be attached to the fiberglass wool with a thin coat of asphalt. Another approach to vapor retardance is to apply a separate 4- to 6-mil polyethylene film over installed insulation. Guardian Fiberglass, Inc. produces a polypropylene scrim kraft for insulation applications.
Such insulation products are generally provided in the form of continuous lengths (packaged as rolls) or of individual panels, or batts, with facing materials on one or both major surfaces to enable the insulation product to be handled more easily and to be fastened in position for insulating purposes, and to minimize dusting of the fiberglass fibers within the insulation product. In most instances, the provision of a facing that forms a vapor barrier is desirable in order to prevent water vapor passing through the insulation product and condensing on a cold surface.
Facing materials may be adhered to the fiberglass fiber blanket in a number of ways. For example, solvent-based or water-based adhesives or hot-melt adhesives may be applied to the facing material or to the surface of the fiberglass wool blanket, with the fiberglass wool blanket and the facing material then being brought together to surface bond the two materials. Alternatively, the facing material itself may be rendered adhesive before application to the fiberglass wool blanket. For example, a thermoplastic material such as a synthetic polymer or a bituminous layer on one surface of the facing material may be heat softened for that purpose. However, the heat treatment of polyethylenexe2x80x94the most commonly used synthetic polymer in this contextxe2x80x94may destroy any water vapor barrier properties it possesses.
A product which has met with some commercial success is a kraft paper/polyethylene vapor barrier manufactured by Owens Corning, which is bonded via the polyethylene to a glass wool blanket. A more sophisticated product consists of an aluminum foil/kraft paper vapor barrier adhesively bonded on its kraft paper surface to a glass wool blanket. However, the aluminum foil incorporated as the vapor barrier renders it much more expensive.
The organization known as ASTM has publishedxe2x80x94under the designation E 96-00 (published July 2000)xe2x80x94a description of test methods to determine water vapor transmission of materials through which the passage of water vapor may be of importance, such as paper and other sheet materials. Those test methods permit the determination of PERM values for the sheet materials. The PERM values reflect the water vapor transmission and permeance of the materials.
Many conventional insulation facing products fail to consistently meet PERM requirements. PERM values greater than 1.0 are considered to be unacceptable for the purposes of the present invention.
The present invention provides a kraft facing for fiberglass insulation that consistently meets PERM requirements.
One embodiment of the present invention is a flexible planar laminate comprising an external support layer of kraft paper to which is adhered a central vapor barrier layer of high density polyethylene (HDPE) or polypropylene, to which is adhered an internal adhesive layer of low density polyethylene (LDPE). The flexible planar laminate preferably comprises from 2 to 10 pounds, most preferably 7 pounds, of HDPE and from 3 to 10 pounds, most preferably 5 pounds, of LDPE per ream (3000 square feet) of kraft paper having a weight of 30 to 50 lbs/ft2. In the flexible planar laminate of this invention, the softening point of the LDPE is from 25 to 125xc2x0 F. and preferably from 25 to 75xc2x0 F. lower than the softening point of the HDPE. When polypropylene is used as the barrier layer, the softening point of the LDPE is 25 to 150xc2x0 F. and preferably from 25 to 75xc2x0 F. lower than the softening point of the polypropylene.
Another embodiment of the present invention is a process for preparing a fiberglass insulation product. This process involves: (a) providing a layer of kraft paper, (b) coating the kraft paper layer with from 2 to 10 pounds of HDPE or of polypropylene per 3000 square feet of said paper to form an HDPE-kraft laminate, (c) coating the HDPE-kraft or PP-kraft laminate with from 3 to 10 pounds of LDPE per 3000 square feet of said HDPE-kraft or PP-kraft laminate to form an LDPE-HDPE (or PP)-kraft laminate, (d) adjusting the temperature of the LDPE-HDPE (or PP)-kraft laminate, e.g. with an infra-red heater, a microwave heater, or a rotating hot roll, so that the LDPE becomes tacky while the HDPE or PP remains solid, (e) providing a layer of fiberglass wool, and (f) contacting the LDPE layer of the LDPE-HDPE (or PP)-kraft laminate with the fiberglass wool layer with pressure and cooling to bond said LDPE-HDPE (or PP)-kraft laminate to said fiberglass wool layer to form a fiberglass insulation product.
Still another embodiment of the present invention is a fiberglass insulation product comprising a layer of fiberglass wool and a flexible planar laminate as described above.
Advantages of the present invention will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.